Patent Document 1 discloses a hydraulic brake system including (a) a hydraulic brake designed to restrain rotation of a wheel, (b) a master cylinder, (c) an accumulator, (d) a pressurization mechanism utilizing a hydraulic pressure in the accumulator and activatable by activation of an electric actuator, and (e) a selective valve designed to select a higher one of a hydraulic pressure in the pressurization mechanism and a hydraulic pressure in the master cylinder to supply the selected hydraulic pressure to a brake cylinder of the hydraulic brake.
Patent Document 2 discloses a hydraulic brake system including (a) hydraulic brakes provided for front right, front left, rear right and rear left wheels of a vehicle and designed to restrain rotations of the wheels, (b) a master cylinder, (c) a mechanical booster provided between the master cylinder and brake cylinders of ones of the hydraulic brakes which are provided for the front right and front left wheels, (d) a high pressure source and an electromagnetic valve that is configured to control a hydraulic pressure produced by the high pressure source.